Over the last ten years there has been a transition to the use of small milling media in conventional media mill processes for the preparation of various paints, pigment dispersions and photgraphic (and other imaging) dispersions. This transition has been made possible due primarily to the improvements in media mill designs (eg. Netzsch LMC mills and Drais DCP mills) which allow the use of media as small as 250 microns (.mu.m). The advantages of small media include more efficient comminution (ie. faster rates of size reduction) and smaller ultimate particle sizes.
Even with the best machine designs available, it is generally not possible to use media smaller than 250 .mu.m due to separator screen plugging and unacceptable pressure build-up due to hydraulic packing of the media. In fact, for most commercial applications, 350 .mu.m media is considered the practical lower limit for most systems. Little or no consideration has been given to further exploit possible advantages of using media smaller than 250 .mu.m.